1. Field of the Invention
The present invention generally relates to multimedia multiplexer devices, and more particularly to a multimedia multiplexer device capable of automatically recognizing and setting parameters to be used for communications.
2. Description of the Prior Art
Recently, there has been considerable activity in the development of private network systems. For example, a private network system has multimedia multiplexer devices that function as the core units in the private network system. Various communications devices are connected to the multimedia multiplexer devices, which are connected to each other via transmission lines. Examples of the communications devices are private branch exchanges, packet switches, and video conference systems.
The communications devices communicate with the multimedia multiplexer devices regarding parameters necessary for transmission of communications therebetween. Examples of these parameters are transmission bit rate (clock frequency), coding method, and frame structure. For example, data encoded by a first coding method and arranged in a first frame format is transferred between the private branch exchange and the multimedia multiplexer device at a first bit rate. Data encoded by a second coding method and arranged in a second frame format is transferred between the packet switch and the multimedia multiplexer device at a second bit rate. In the above manner, the communications device communicates with the multimedia multiplexer devices regarding the parameters inherent in the types of multimedia (communications devices).
Further, the multimedia multiplexer devices communicate with each other via respective line terminating devices connected to each other via the transmission lines. The multimedia multiplexer devices communicate with the respective line terminating devices according to respective parameters.
It can be seen from the above that the multimedia multiplexer devices are required to provide for all the parameters and select suitable parameters in response to a request for communications.
FIG. 1 is a block diagram of a conventional private network system, and FIG. 2 is a block diagram of the structure of each multimedia multiplexer device.
Referring to FIG. 1, the private network system includes multimedia multiplexer devices (MUX) 1 and 8, which are installed in factories A and B of a company, respectively. The MUXs 1 and 8 communicate with each other via line terminating units (CSU) 5 and 7 and a transmission line L. A private branch exchange (PBX) 2, a packet switch (PKT SW) 3, and a video conference system (VCS) are connected to the MUX 1. Similarly, a private branch exchange (PBX) 9, a packet switch (PKT SW) 10, and a video conference switch (VCS) 11 are connected to the MUX 8. Telephone sets, facsimile machines and so on are connected to the PBXs 2 and 9.
Voice data is transferred between the PBX 2 (9) and the MUX 1 (8) according to predetermined parameters inherent in transmission of the voice data. Packet data is transferred between the packet switch 3 (10) and the MUX 1 (8) according to predetermined parameters inherent in transmission of the packet data. Voice data and video data are transferred between the video conference system 4 (11) and the MUX 1 (8) according to predetermined parameters inherent in transmission of the voice data and video data. The MUX 1 (8) multiplexes signals received from the devices 2 (9), 3 (10) and 4 (11) to thereby generate a multiplexed signal, which is sent to the line terminating unit 5 (7). The MUX 1 (8) also has the function of demultiplexing a multiplexed signal received from the line terminating unit 5 (7) into original signals sent from the PBX 9 (2), 10 (3) and 11 (4).
The line terminating unit 5 (7) establishes an interface between the MUX 1 (8) and the transmission line L. The multiplexed signal is transferred between the MUX 1 (8) and the line terminating unit 5 (7) according to predetermined parameters inherent in transmission of the multiplexed signal.
A network managing processor (NMP) 6, which is connected to the MUX 1, manages the entire private network system. An external storage device 12 is connected to the network managing unit 6.
The MUX 1 has a structure shown in FIG. 2. The MUX 8 has the same structure as the MUX 1. The MUX 1 includes a device controller 13, a network port unit 14, line setting units 15 and an interface unit 16 where m is an integer. The device controller 13 is connected to the structural elements in the MUX 1 via control buses indicated by dotted lines, and performs the overall control of the MUX 1. The network port unit 14 multiplexes data from the line setting units 15 via data buses indicated by solid lines, and sends a multiplexed signal to the line terminating unit 5. Each of the line setting units 15 transfers data from the communications devices, such as the PBX 2, the packet switch 3 and the video conference system 4, to the network port unit 14. The MUX 1 communicates with the network managing processor 6 via the interface unit 16.
Conventionally, all the parameters used in the private network system are studied and the appropriate values of the parameters are determined before starting to operate the private network system or new communications devices newly connected to the MUX. More particularly, the maintenance person or the user must recognize the parameters necessary for transmission of data between each of the devices 2 (9), 3 (10) and 4 (11) and the MUX 1 (8) and selects the appropriate values of the parameters. The values of the parameters (parameter information) are determined by the network managing processor 6 and recorded in the external storage device 12. Then, the parameter information is read from the external storage device 12 and loaded in the structural elements of the MUX 1 under control of the network managing processor 6.
For example, if a second PBX is connected to the MUX 1 in addition to the (first) PBX 2, the maintenance person or the user recognizes what parameters are used to transfer data between the second PBX and the MUX 1, and determines appropriate values of the parameters. Then, the maintenance person or the user formulates information concerning the identified parameters (parameter values) and records the parameter information in the external storage device 12. Then, the parameter information is loaded in the structural elements of the MUX 1 under control of the network managing processor 6. A similar procedure is needed if the existing communications devices are modified.
As described above, it is necessary to manually recognize what parameters are used for data transfer and manually determine the appropriate values of these parameters.